The invention relates to a voltage regulator for an alternator. A voltage regulator for an alternator is known which charges a battery via a charging cable and supplies a vehicle mains with voltage. The output voltage of an alternator in a motor vehicle which is used for charging a battery and for supplying the consuming devices in the vehicle is controlled to remain at a constant value with the aid of a voltage regulator. Since the charging voltage required for optimal charging of the battery at low temperatures is higher than that required at high temperatures, the charging voltage and accordingly also the alternator output voltage are adapted to the temperature of the battery. For this purpose it is known e.g. from DE-0S 32 43 075 to measure the temperature of the battery with a temperature sensor which is fastened in the immediate vicinity of the battery and to influence the charging voltage with the aid of the output signal of this temperature sensor. A separate temperature sensor which must be connected by a relatively long cable from the vicinity of the battery to the regulator is disadvantageous. This results in added costs and is troublesome.
Since a drop in voltage which should likewise be taken into account for an optimal charging of the battery, occurs on the charging cable between the alternator and the battery, it is known from DE-OS 32 43 075 to measure the voltage at the positive pole of the battery also. However, an additional sensor and connection cable is required for this.